Graphene entrainment in a host

ABSTRACT

This is generally a method of producing graphene-containing suspensions of flakes of high quality graphene/graphite oxides and method of producing graphene/graphite oxides. Both the exfoliating graphite into flakes and oxidizing the graphite flakes and the preparation and suspension of the flakes can be done with high volume production and at a low cost.

TECHNICAL FIELD OF THE INVENTION

The present invention relates in general to the field of graphene, andmore particularly, to transitioning graphene into a variety ofmacroscale mechanical structures.

BACKGROUND OF THE INVENTION

Without limiting the scope of the invention, its background is describedin connection with composite materials.

U.S. Pat. No. 8,216,541, issued to Jang, et al. is directed to a processfor producing dispersible and conductive nano-graphene platelets fromnon-oxidized graphitic materials. Briefly, these inventors are said toteach a process for producing nano-graphene platelets (NGPs) that areboth dispersible and electrically conducting. The process is said toinclude: (a) preparing a pristine NGP material from a graphiticmaterial; and (b) subjecting the pristine NGP material to an oxidationtreatment to obtain the dispersible NGP material, wherein the NGPmaterial has an oxygen content no greater than 25% by weight. Theconductive NGPs are said to find applications in transparent electrodesfor solar cells or flat panel displays, additives for battery andsupercapacitor electrodes, conductive nanocomposite for electromagneticwave interference (EMI) shielding and static charge dissipation.

United States Patent Publication No. 20120298620, filed by Jiang, etal., is directed to a method for making graphene composite structure.Briefly the method is said to include providing a metal substrateincluding a first surface and a second surface opposite to the firstsurface, growing a graphene film on the first surface of the metalsubstrate by a CVD method, providing a polymer layer on the graphenefilm and combining the polymer layer with the graphene film, and forminga plurality of stripped electrodes by etching the metal substrate fromthe second surface.

Finally, United States Patent Publication No. 20120228555, filed byCheng, et al., is directed to a method of making graphene. Briefly, theapplication is said to disclose a method for making graphene byproviding a starting material and heating the starting material for atime and to a temperature effective to produce graphene. In certainembodiments the applicants are said to use starting materials thatinclude carbonaceous materials used in conjunction with, or comprising,sulfur, and essentially free of a transition metal. The grapheneproduced by the current method is said to be used to coatgraphene-coatable materials.

SUMMARY OF THE INVENTION

In one embodiment the present invention includes a method of making agraphene suspension, comprising: preparing graphene flakes with asurface area to thickness ratio greater than 300 Angstroms, andthickness of less than 160 Angstroms, wherein the graphene flakes haveno significant physical surface distortions and have a surface polarity;preparing a polar or nonpolar fluid having the same polarity as saidgraphene flakes; and suspending said graphene flakes in said fluid bymixing until the suspension is substantially uniform. In one aspect, thesuspension is a carbon allotrope. In another aspect, 95% of the flakesare from about 0.8 to 16 nanometers in thickness. In another aspect, 95%of the flakes have a surface area to thickness ratio of a minimum of 300Angstroms. In another aspect, the maximum dimension of the flakesbetween 220 Angstroms and 100 microns. In another aspect, the Grapheneflake has only edge oxidation. In another aspect, the method furthercomprises adding a bonding host and the flake surfaces have the samepolarity as the bonding host. In another aspect, the mechanicallyexfoliating graphite into graphene flakes in done in a stirred mediamill, and the stirred media mill is an Attrition mill or ball mill. Inanother aspect, the method outputs are substantially limited tosubstantially flat graphene flakes and water.

Another embodiment the present invention includes a method of making agraphene suspension, comprising: preparing graphene flakes with asurface area to thickness ratio greater than 300 Angstroms, andthickness of less than 160 Angstroms, wherein the graphene flakes aresubstantially planar and have a surface polarity; and suspending saidgraphene flakes in a fluid by mixing until the suspension issubstantially uniform. In one aspect, the suspension is a carbonallotrope. In another aspect, 95% of the flakes are from about 0.8 to 16nanometers in thickness. In another aspect, 95% of the flakes have asurface area to thickness ratio of a minimum of 300 Angstroms. Inanother aspect, the maximum dimension of the flakes between 220Angstroms and 100 microns. In another aspect, the Graphene flake hasonly edge oxidation. In another aspect, the method further comprisesadding a bonding host and the flake surfaces have the same polarity asthe bonding host. In another aspect, the mechanically exfoliatinggraphite into graphene flakes in done in a stirred media mill, and thestirred media mill is an Attrition mill or ball mill. In another aspect,the method outputs are substantially limited to substantially flatgraphene flakes and water.

Yet another embodiment of the present invention includes a graphenesuspension made by a method comprising: preparing graphene flakes with asurface area to thickness ratio greater than 300 Angstroms, andthickness of less than 160 Angstroms, wherein the graphene flakes haveno significant physical surface distortions and have a surface polarity;preparing a polar or nonpolar fluid having the same polarity as saidgraphene flakes; and suspending said graphene flakes in said fluid bymixing until the suspension is substantially uniform. In one aspect, 95%of the flakes are from about 0.8 to 16 nanometers in thickness. Inanother aspect, 95% of the flakes have a surface area to thickness ratioof a minimum of 300 Angstroms. In another aspect, the maximum dimensionof the flakes between 220 Angstroms and 100 microns.

Yet another embodiment of the present invention includes a graphenesuspension made by a method comprising: preparing graphene flakes with asurface area to thickness ratio greater than 300 Angstroms, andthickness of less than 160 Angstroms, wherein the graphene flakes aresubstantially planar and have a surface polarity; and suspending saidgraphene flakes in a fluid by mixing until the suspension issubstantially uniform. In one aspect, 95% of the flakes are from about0.8 to 16 nanometers in thickness. In another aspect, 95% of the flakeshave a surface area to thickness ratio of a minimum of 300 Angstroms. Inanother aspect, the maximum dimension of the flakes between 220Angstroms and 100 microns.

DETAILED DESCRIPTION OF THE INVENTION

While the making and using of various embodiments of the presentinvention are discussed in detail below, it should be appreciated thatthe present invention provides many applicable inventive concepts thatcan be embodied in a wide variety of specific contexts. The specificembodiments discussed herein are merely illustrative of specific ways tomake and use the invention and do not delimit the scope of theinvention.

To facilitate the understanding of this invention, a number of terms aredefined below. Terms defined herein have meanings as commonly understoodby a person of ordinary skill in the areas relevant to the presentinvention. Terms such as “a”, “an” and “the” are not intended to referto only a singular entity, but include the general class of which aspecific example may be used for illustration. The terminology herein isused to describe specific embodiments of the invention, but their usagedoes not delimit the invention, except as outlined in the claims.

Despite these nanoscale mechanical properties, graphene previously hadnot been able to be transitioned to a macro-scale mechanical structure.The process of producing a loaded host did not translate to a viablecomposite structure. The inability to translate the technology to aviable composite structure was a combination of technical issues andcost factors, including uniform distribution of the suspension in thehost material. The technical limitation included stochastic processes inthe curing of the host while obtaining a distribution of the suspension.Curing of the host material resulted in random shrinkage phenomena,which was exacerbated in larger composite structures/devices. If asuspension was added to the host prior to curing, polymerization,hydrolyzation or other thermal, mechanical, chemical processes thatinitiation either long-range or short-range ordering bonding thedistribution of the non-uniform suspension creating weak regions andfailure points in the loaded host material.

Graphene is an allotrope of carbon. Graphene's purest form is aone-atom-thick planar sheet of sp²-bonded carbon atoms that are denselypacked in a honeycomb or hexagonal crystal lattice. Graphene used as anadditive have been shown superior mechanical, chemical, thermal, gasbarrier, electrical, flame retardant and other properties compared tothe native host. Improvement in the physicochemical properties of thehost depends on: 1) a uniform distribution and entrainment of thegraphene flake, 2) optimizing the interfacial bonding between thegraphene flake and host's matrix, 3) removal of gasses entrained in thehost during processing, 4) optimizing the additive's innate properties,e.g. flatness, and/or 5) optimizing the thickness to surface-area ratioof the graphene flake.

Optimal properties of the graphene flake: We have found that theperformance of a graphene flake is dominated by both the texture and thesurface and edge oxidation/functionalization. A Hummer's based processproduces graphene flakes that have both a surface and edge oxidation.The degree of oxidation and exfoliation inherent in the Hummer's ormodified based Hummer's process results in permanent corrugateddisfiguration of the graphene flake. The combination low yield, highcost and inconsistent performance makes the approach not viable. Thepermanent corrugated structure degrades the chemical, mechanical,electrical and thermal properties of graphene flake. Hence a surfaceoxidized graphene flake has lower performance than the single-layergraphene originally demonstrated when the graphene was first discoveredin 2007. This can explain by simple theoretical analysis where thecorrugated structure induces different shearing and loading forces tothe surrounding host as the corrugated structure gives a third dimensionto the ideal two dimension graphene structure. In the transmission ofphonons or electrons the ideal structure is a uniform flat large areagraphene structure. This is illustrated by the development activities ofthe semiconductor industry as they focused chemical vapor depositionthin film generated graphene material. A corrugated structure inducesresistance and inductance to the transmission of phonons and electronshence a planar flake has higher performance in the electron and phonontransmission relative to a corrugated structure in the surface oxidizedgraphene flake.

This can be a method of making a graphene suspension, comprising:preparing graphene flakes with a surface area to thickness ratio greaterthan 300 Angstroms, and thickness of less than 160 Angstroms, whereinthe graphene flakes have no significant physical surface distortions andhave a surface polarity; preparing a polar or nonpolar fluid having thesame polarity as said graphene flakes; suspending said graphene flakesin said fluid by mixing until the suspension is substantially uniform.

In one embodiment, the suspension is a carbon allotrope; 95% of theflakes are from about 0.1 to 16 nanometers in thickness; 95% of theflakes have a surface area to thickness ratio of a minimum of 300Angstroms; the maximum dimension of the flakes between 220 Angstroms and100 microns; the Graphene flake has only edge oxidation; the flakesurface has the same polarity as the bonding host; the mechanicallyexfoliating graphite into graphene flakes in done in a stirred mediamill, and the stirred media mill is an Attrition mill or ball mill;and/or the method outputs are substantially limited to substantiallyflat graphene flakes and water.

The present invention also includes a method of making a graphenesuspension, comprising: Preparing graphene flakes with a surface area tothickness ratio greater than 300 Angstroms, and thickness of less than160 Angstroms, wherein the graphene flakes are substantially planar andhave a surface polarity; Suspending said graphene flakes in said fluidby mixing until the suspension is substantially uniform.

Recent publications have shown one possible rout to produce a noncorrugated graphene through the of ball milling crystalline graphitewith dry ice the chemo-mechanical processing of the crystalline graphiteproduces edge oxidized graphene flakes. This process shows thefeasibility of an edge-only oxidized graphene flake but cost of thisprocessing is more expensive as required by a commodity additive market.Note that planar graphene graphite for research has also been producedby manually separating one layer at time from a piece of crystallinegraphite. Needless to say this is far too slow and too expensive forcommercial production. The Hummer's based process produces graphene thatis not planar, generally weaken the graphite in a host.

Optimizing the interfacial bonding between the graphene flake and host'smatrix. Optimizing the interfacial bonding requires the two criticalaspects, first is the providing of a planar pristine surface that is notdistorted through the graphene production process. Secondly is themodification of the chemistry of the additive to allow full entrainmentof the additive in host's matrix. For graphene this can be the modifyingthe OOH group with other chemical functionality to tailor the additiveto be hydrophilic or hydrophobic and/or create a functional group on theadditive that is similar to the host's chemistry (i.e., polarity,hydrophilicity, etc.). Creating the correct hydrophobicity allows thegraphene additive to be maintained in suspension in a variety of commonsolvent hosts prior to long or short range ordering or bonding (e.g. asolid). Functionalizing the graphene additive with a similar chemistryto the host allows the graphene additive to be directly incorporated inthe long or short range ordering or bonding. The fluids can includeplastics, metals, ceramics and glass.

Thickness to surface area ratio of the graphene flake: Using a planargraphene flake the next issue of implementing in a host is the thicknessto surface-area of the graphene flake. The thickness to surface-arearatio of the graphene flake plays a significant ability in the grapheneflakes ability to positively impact the host's properties.

This large surface with a modest thickness is conceptually comparable tothe ideal larger area monolayer need by the semiconductor industry. Alarge flat flake will conduct better phonons and electrons better thanthe host alone. A multi-layer graphene flake held bonded even by withvan der Waal forces is more desirable than a thin flake surround by aninsulating host. This is true for mechanical applications as well. Aslong as there is a larger surface area to thickness ratio the graphenecan mitigate and distribute a mechanical load giving the host enhancedmechanical properties, increased tensile, shear, and flexural strength.The ability to achieve substantial enhancement of the host's mechanicalproperties can e.g. be obtained with a flake with an area of 48,400 Å²with a flake thickness to 160 Å to 200 Angstroms. A 48,400 Å² area flakewith a thickness of 160 Å has a surface area to thickness ratio of about300 Angstroms can also provide enhancement to the host's mechanicalproperties (preferably 95% of the graphene flakes of the presentinvention have a surface area to thickness ratio of a minimum of 300Angstroms).

In some embodiments our flake thicknesses are 16 nanometers or less astoo many layers significantly reduce the tensile strength (preferably95% of the graphene flakes of the present invention are from about 0.8to 16 nanometers), and our surface area to thickness ratio is greaterthan 48400 to 1 Angstroms. Preferably, the maximum dimension of theflake varies between 220 Angstroms and 100 microns. This requiresprecise process control or a process that allows separation of thegraphene flakes by surface area and/or thickness.

Uniform distribution and entrainment: The third aspect of obtaining aneffective uniform distribution and entrainment of graphene flake as anadditive in the host fluid is the aggressively mixing the flake into thehost fluid (for example, under an at least partial vacuum), prior toreacting, casting or otherwise causing the host to become ordered bythermal, chemical, electrical or other processes that induce order orbonding in the host, e.g. solidified of gelled. In some embodiments,epoxy that is dried is used, and then thermally set after mixing. In oneembodiment of the present invention, greater than 6% loading of grapheneis used (e.g. between 6 and 35%). Studies on attaining increased potencyof fillers by using different mixing techniques, modification of polymerbackbone or filler surface, use of functional polymers and couplingagents, etc. Graphene, has low surface energy as compared withcrystalline graphite (the cost-effective precursor for graphene/grapheneoxide). One of the routes to overcome this limitation is thefunctionalization of flake surface, which results in significantenhancement of the mechanical and electrical properties of polymercomposites. As graphene is being entrained in a host a mild vacuum maybe applied to prevent gasses from being incorporated in the host. Theformation of gas bubbles increase resistance to phonon and electrontranspiration in addition creating light scattering centers andmechanical defect sights in a host.

Obtaining consistent size and thickness can require controlledpre-processing (e.g., milling and separation) of the crystallinegraphite. Chemo-mechanical processing can use crystalline graphite witha mild oxidizing agent in conjunction with mechanical energy (milling)for synthesis of graphene.

The mechanical energy in conjunction with a mild oxidizing environmentcan produce edge oxidation of the graphene minimizing the surfaceoxidation and mechanical defects generated in a Hummer's based process.

Graphite (TC306, 30 g) can be used as the starting material for thegraphene chemo-mechanical process. Chemo-mechanical process can be donein what is generically referred to as a “stirred ball mill.” A usefuland simple equation describing the grinding momentum is M×V(mass×velocity), which enables us to see how an ball milling use up to 6lbs (2.7 Kg) (or ˜2,600 stainless steel balls) of 0.25″ diameterstainless steel balls weighing 1 g each. Milling in a closed chamber for360 minutes at 2,000 RPM or less. When grinding in the ball milling asthe balls (media) in their random movement are spinning in differentrotation and, therefore, exerting shearing forces on the crystallinegraphite. The resulting graphene preferably has edge-only oxidizedflakes with a pristine surface free of distortions or corrugations withlow surface energies allowing for easier incorporation and entrainmentin a host with enhance graphene physical properties.

The oxidation of the graphene can occur from a wide range of methods ofmaking graphene oxide, comprising: Putting crystalline graphite and anatomizer or aerosolized oxidizing agent in a mill, wherein the atomizeror aerosolized oxidizing exfoliating agent contains only carbon, oxygen,hydrogen and combinations thereof; Milling said crystalline graphite andatomizer or aerosolized oxidizing exfoliating agent to produce planargraphene flakes having a thickness of less than 160 Angstroms; andSuspending said graphene flakes in a fluid to remove the graphene flakesfrom the mill.

This can be a technique for low cost, mass-production of a partiallyoxidized to fully oxidized graphite/graphene using mechanical processing(Attritor Mill) in conjunction with a water soluble exfoliating agent,such as kaolin clay powder and at least one of atomizer or aerosolizedcarbolic acid or oxalic acid (C₂H₂O₄), acetic acid, carbonic acid orethanoic (CH₃CO)₂O, and citric acid. Aerosolization can be accomplishedby an Ultrasonic Atomizer Processor, ultrasonic spray & atomizationsystem made by U&STAR Ultrasonic Technology. An ultrasonic spray system,uses an ultrasound technology to atomize liquid or powders generatedfrom ultrasonic energy that scattered the liquid forming dropletsranging microns to more than 100 microns. Liquid droplets that maycontain powders and soluble matter, promoting chemical reaction, andspraying. This ultrasonic spray atomization has low power, large volume.An ultrasonic spray system widely applied on kinds of industrialapplications including ultrasonic spraying liquid, metal power waternebulization or atomization. The controlled small droplet sizes providea high surface to volume ratio enhancing efficiency and control chemicalreactions.

The atomizer or aerosolized oxidizing agent is injected into a mill inaddition to the crystalline graphite. Directly milling of graphitepowder without concentrated acid, for aerosolized oxidizing, to producehigh quality oxidized graphene. After milling the crystalline graphitewith an aerosolized oxidizing agent is injected into the attritor millfor a minimum of 30 min to produce an aqueous slurry. The aqueous slurrycontains a mild acid that breaks down into water and graphite. The watercan dissolve the water-soluble exfoliating agent. An example of awater-soluble exfoliating agent is kaolin clay powder. The mildaerosolized oxidizing agent produces oxidized graphene with nodistortion or texturing. Textured graphene oxide produces significantproblems when depositing the graphene oxide, using the graphene oxide ina suspension or as an additive to other materials.

Directly milling of graphite powder with a chemically stable gaseousoxidizing agent in addition to the gaseous oxidizing agent awater-soluble exfoliating agent, such as kaolin clay powder can be addedto process to produce high quality edge oxidized graphene. Afterexfoliating the crystalline graphite in the Attritor mill for 90 minwith steel balls and chemically stable gaseous oxidizing agent isintroduced. Once the carbon dioxide is released and the pressure in theAttritor exceeds two atmospheres the chemo-mechanical processinginitiate graphene oxidation resulting edge oxidized graphene. As thechemo-mechanical processing continues pressure in the chamber decreasesin the Attritor mill. Keeping the Attritor mill at an elevate pressureduring the oxidation process enables a higher level of oxidation of thegraphene flakes.

Additionally graphene oxide may be made, by: Putting crystallinegraphite, and vapor phase oxidizing agent in a mill, wherein theoxidizing agent comprises nitrogen, carbon, oxygen, hydrogen and/orcombinations thereof; Milling said crystalline graphite and vapor phaseoxidizing agent to produce planar graphene flakes having a thickness ofless than 160 Angstroms; and Suspending said graphene flakes in a fluidto remove the graphene flakes from the mill.

This can also be a method of making graphene oxide, comprising: Puttingcrystalline graphite, mineral-based exfoliating media and vapor phaseoxidizing agent in a mill, wherein the oxidizing agent comprisesnitrogen, carbon, oxygen, hydrogen and/or combinations thereof; Millingsaid crystalline graphite, mineral-based exfoliating media and vaporphase oxidizing agent where water vapor or liquid is combined to producea mild acidic slurry where the slurry enhances the exfoliation of thegraphite to produce planar graphene flakes having a thickness of lessthan 160 Angstroms; and additional water is added at the end of theprocess to remove the water soluble exfoliating agent leaving water andgraphene flakes.

This can be a method of making graphene oxide, comprising: Puttingcrystalline graphite and anhydrous oxidizing exfoliating agent in amill, wherein the anhydrous oxidizing exfoliating agent contains onlycarbon, oxygen, hydrogen and combinations thereof; Milling saidcrystalline graphite and anhydrous oxidizing exfoliating agent toproduce planar graphene flakes having a thickness of less than 160Angstroms; and Suspending said graphene flakes in a fluid to remove thegraphene flakes from the mill.

Preferably, the milling is done in a stirred mill; the stirred mill isan Attrition mill or Attritor; the method outputs are substantiallylimited to substantially flat graphene flakes and carbon, oxygen,hydrogen and combinations thereof; and/or the anhydrous oxidizingexfoliating agent is at least one of crystal carbolic acid or anhydrousoxalic acid (C₂H₂O₄), Acetic anhydride, or ethanoic anhydride (CH₃CO)₂O,and anhydrous citric acid powder.

If the suspension application requires a narrow size distribution theedge oxide graphene can be chemically separated via acidic precipitationby titrating hydrochloric acid into the bath the larger(thicker/heavier) material comes out of suspension first creating anarrow graphene oxide flake distribution. The particle size can bemonitored during this process by Dynamic Light Scattering measurementtool. Dynamic Light Scattering tools can resolve particle sizes down to30 Å.

Preferably, the surface area to thickness ratio should be greater thanabout 300 to have a positive impact on the host as a suspension. The pHof the water containing the oxidized graphite/graphene can range from 5to 9 while maintaining the suspension of the media the pH of theresulting water/graphene mixture is typically is about 7. Achemo-mechanical can be controlled to process graphene with oxidizationof from 1% to 35%. Unless otherwise indicated or produced by the Hummerprocess, the term “graphene” as used herein means graphene withoxidization of from 1% to 35%. The functionalization can be COOH on theedge carbons preserving the graphene structure.

Oxidized graphite produced by this method is typically hydrophilic andeasily suspended in a neutral aqueous solution. The oxidized graphitecan be kept in suspension until varying the pH of the solution.

A ball mill operating with less than or equal to 2,000 RPM can begenerally sufficient to prevent agglomeration of the graphene adheringto the milling balls or tank.

The graphene can be combined with the host material in a mechanicalagitation process.

Graphene is diamagnetic and as such dynamic magnetic fields can be usedto enhance orientation and mixing along in addition other method suchas: melt blending, counter rotating screw, sonication or other mixingprocesses of the graphene additive into the host material prior toinducing ordering or bonding in the host. The entrainment and uniformdispersement preferably uses a minimum of 30 minutes of and less than600 minutes in a ball mill.

The resulting graphene entrained host can be the cast, extruded orotherwise processed into the final product by inducing long or shortrange ordering or bonding through chemical, thermal, electrical,shearing, or mechanical treatments.

Although the present invention and its advantages have been described indetail, it should be understood that various changes, substitutions andalterations can be made herein without departing from the spirit andscope of the invention as defined by the appended claims. Moreover, thescope of the present application is not intended to be limited to theparticular embodiments of the process, machine, manufacture, compositionof matter, means, methods and steps described in the specification. Asone of ordinary skill in the art will readily appreciate from thedisclosure of the present invention, processes, machines, manufacture,compositions of matter, means, methods, or steps, presently existing orlater to be developed, that perform substantially the same function orachieve substantially the same result as the corresponding embodimentsdescribed herein may be utilized according to the present invention.Accordingly, the appended claims are intended to include within theirscope such processes, machines, manufacture, compositions of matter,means, methods, or steps.

It is contemplated that any embodiment discussed in this specificationcan be implemented with respect to any method, kit, reagent, orcomposition of the invention, and vice versa. Furthermore, compositionsof the invention can be used to achieve methods of the invention.

It will be understood that particular embodiments described herein areshown by way of illustration and not as limitations of the invention.The principal features of this invention can be employed in variousembodiments without departing from the scope of the invention. Thoseskilled in the art will recognize, or be able to ascertain using no morethan routine experimentation, numerous equivalents to the specificprocedures described herein. Such equivalents are considered to bewithin the scope of this invention and are covered by the claims.

All publications and patent applications mentioned in the specificationare indicative of the level of skill of those skilled in the art towhich this invention pertains. All publications and patent applicationsare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

The use of the word “a” or “an” when used in conjunction with the term“comprising” in the claims and/or the specification may mean “one,” butit is also consistent with the meaning of “one or more,” “at least one,”and “one or more than one.” The use of the term “or” in the claims isused to mean “and/or” unless explicitly indicated to refer toalternatives only or the alternatives are mutually exclusive, althoughthe disclosure supports a definition that refers to only alternativesand “and/or.” Throughout this application, the term “about” is used toindicate that a value includes the inherent variation of error for thedevice, the method being employed to determine the value, or thevariation that exists among the study subjects.

As used in this specification and claim(s), the words “comprising” (andany form of comprising, such as “comprise” and “comprises”), “having”(and any form of having, such as “have” and “has”), “including” (and anyform of including, such as “includes” and “include”) or “containing”(and any form of containing, such as “contains” and “contain”) areinclusive or open-ended and do not exclude additional, unrecitedelements or method steps. In embodiments of any of the compositions andmethods provided herein, “comprising” may be replaced with “consistingessentially of” or “consisting of”. As used herein, the phrase“consisting essentially of” requires the specified integer(s) or stepsas well as those that do not materially affect the character or functionof the claimed invention. As used herein, the term “consisting” is usedto indicate the presence of the recited integer (e.g., a feature, anelement, a characteristic, a property, a method/process step or alimitation) or group of integers (e.g., feature(s), element(s),characteristic(s), propertie(s), method/process steps or limitation(s))only.

The term “or combinations thereof” as used herein refers to allpermutations and combinations of the listed items preceding the term.For example, “A, B, C, or combinations thereof” is intended to includeat least one of: A, B, C, AB, AC, BC, or ABC, and if order is importantin a particular context, also BA, CA, CB, CBA, BCA, ACB, BAC, or CAB.Continuing with this example, expressly included are combinations thatcontain repeats of one or more item or term, such as BB, AAA, AB, BBC,AAABCCCC, CBBAAA, CABABB, and so forth. The skilled artisan willunderstand that typically there is no limit on the number of items orterms in any combination, unless otherwise apparent from the context.

As used herein, words of approximation such as, without limitation,“about”, “substantial” or “substantially” refers to a condition thatwhen so modified is understood to not necessarily be absolute or perfectbut would be considered close enough to those of ordinary skill in theart to warrant designating the condition as being present. The extent towhich the description may vary will depend on how great a change can beinstituted and still have one of ordinary skilled in the art recognizethe modified feature as still having the required characteristics andcapabilities of the unmodified feature. In general, but subject to thepreceding discussion, a numerical value herein that is modified by aword of approximation such as “about” may vary from the stated value byat least ±1, 2, 3, 4, 5, 6, 7, 10, 12 or 15%.

All of the compositions and/or methods disclosed and claimed herein canbe made and executed without undue experimentation in light of thepresent disclosure. While the compositions and methods of this inventionhave been described in terms of preferred embodiments, it will beapparent to those of skill in the art that variations may be applied tothe compositions and/or methods and in the steps or in the sequence ofsteps of the method described herein without departing from the concept,spirit and scope of the invention. All such similar substitutes andmodifications apparent to those skilled in the art are deemed to bewithin the spirit, scope and concept of the invention as defined by theappended claims.

What is claimed is:
 1. A method of making a graphene suspension,comprising: preparing graphene flakes with a surface area to thicknessratio greater than 300 Angstroms, and thickness of less than 160Angstroms, without concentrated acid, wherein the graphene flakes areplanar, have no physical distortions or corrugations, have only edgeoxidation, and have a surface polarity; suspending said graphene flakesin a fluid by mixing until the suspension is substantially uniform; andwherein the graphene flakes have an oxidization greater than or equal to1% and less than 5%.
 2. The method of claim 1, wherein 95% of the flakesare from about 0.8 to 16 nanometers in thickness.
 3. The method of claim1, wherein 95% of the flakes have the surface area to thickness ratiogreater than 300 Angstroms.
 4. The method of claim 1, wherein a maximumdimension of the graphene flakes is between 220 Angstroms and 100microns.
 5. The method of claim 1, wherein the method outputs aresubstantially limited to flat graphene flakes and water.
 6. A graphenesuspension made by a method comprising: preparing graphene flakes with asurface area to thickness ratio greater than 300 Angstroms, andthickness of less than 160 Angstroms, without concentrated acid, whereinthe graphene flakes are planar, have no physical distortions orcorrugations, have only edge oxidation, and have a surface polarity;suspending said graphene flakes in a fluid by mixing until thesuspension is substantially uniform; and wherein the graphene flakeshave an oxidization of greater than or equal to 1% and less than 5%. 7.The method of claim 6, wherein 95% of the flakes are from about 0.8 to16 nanometers in thickness.
 8. The method of claim 6, wherein 95% of theflakes have the surface area to thickness ratio greater than 300Angstroms.
 9. The method of claim 6, wherein a maximum dimension of thegraphene flakes is between 220 Angstroms and 100 microns.